The present invention relates to a charged particle beam apparatus, for example, an apparatus such as a scanning electron microscope (SEM) for observing a fine pattern on a semiconductor or a general specimen, and a defect inspection apparatus for measuring electrical properties of an electronic device using a fine probe, and more particularly, to a field of view determining method for bringing a probe into contact with a specimen using an image-shift function of a charged particle beam apparatus, and a defect inspection apparatus using the field of view determining method.
Conventionally, known inspection apparatuses for detecting electrical defects in fine electronic circuits formed on semiconductor chips include inspection apparatuses such as an electron beam tester, i.e., EB tester, a probing apparatus, and the like. The EB tester is an apparatus which irradiates an electron beam onto a site under measurement, and detects electrically defective sites of an LSI, taking advantage of the fact that the amount of secondary electrons generated from a site under measurement varies depending on a voltage at the site under measurement. The probing apparatus in turn is an apparatus which brings a plurality of probes or mechanical probes, arranged to match the positions of property measuring pads of an LSI, into contact with measuring pads and plugs to measure the electrical properties of the LSI. With these EB tester and probing apparatus, an operator manually confirms a site with which a probe should be brought into contact, while viewing an image of wires such as an optical microscope (OM) image, a SEM image and the like.
In recent years, increasingly complicated circuit patterns have been formed on semiconductor devices such as LSI's, thereby making it more and more difficult to move a probe to an optimal probing position in a short time. To overcome the difficulties, a technique called “CAD navigation” displays the wiring layout of a semiconductor device in agreement with an actual image of the semiconductor device, referenced by an operator, during a probing operation to reduce a time required for the probing operation.
The SEM image is observed using a scanning electron microscope which scans a primary electron beam on a specimen or semiconductor to capture a scanned image of a fine pattern on the specimen. In order to correctly move a scan area or field of view of the primary electron beam to a point under observation on a specimen, an apparatus intended to observe a fine pattern on the specimen has an image-shift function which electrically deflects the primary electron beam to electrically move a view area in a range of several μm to approximately 10 μm using deflectors systems in series.
Also, since the image-shift function directs the primary electron beam obliquely into an objective lens, off-axis aberrations of the objective lens cause a degradation in the resolution of SEM images. To solve this problem, JP-A-10-247465, for example, discloses a technique for removing the off-axis aberrations as a function of an image-shift amount. Particularly, observations on patterned specimen such as semiconductors are generally made on the order of sub-nanometers or nanometers using low accelerating voltages equal to or lower than 5 kV in order to prevent the specimen from being charged up. When the image-shift function is used for the foregoing purposes under the foregoing conditions, it is necessary to reduce off-axis chromatic aberration and chromatic aberration associated with image-shift deflection.
When the image-shift function is not used, i.e., when the object point of an objective lens does not move, chromatic aberration of the objective lens is effectively reduced to improve the resolution by a retarding method which involves applying a negative voltage to a specimen, or by a boosting method which involves applying a positive voltage into an objective lens. On the other hand, when a specimen is irradiated with an oblique primary electron beam, i.e., in beam tilting, the primary electron beam is intentionally directed out of the axis of an objective lens to generate chromatic aberration, and the chromatic aberration is canceled out using an electrostatic and magnetic multipolor, as disclosed, for example, in JP-A-2001-15055.
While the aforementioned image-shift based movements of the field of view can be substituted by mechanical movements of a DUT stage, the image-shift function is superior in terms of the moving speed and accuracy. Even if the specimen stage (DUT) stage is improved in moving accuracy, mechanical movements cause vibrations at all times. Mechanical vibrations, if any, could damage probes because several probes are often simultaneously brought into contact with measurement plugs during a simultaneous observation in the same SEM field before other probes are brought into contact.
Thus, the operability of a defect analyzer will be significantly improved to reduce a burden on the user if the primary electron beam can be irradiated to a widest possible area, and if the CAD navigation function can be associated with the image-shift function which reduces chromatic aberration.